Spectral sensitivities for various components or channels of an ambient color sensor do not often match those of the human visual system. As a result, additional mathematical steps in the form of sensor calibration are necessary to obtain accurate color coordinate value outputs. For example, a color conversion matrix can be used to convert color component values provided by the ambient color sensor into coordinates for standard color spaces (for example, CIE 1931 XYZ tristimulus values). However, the conversion matrix tends to differ widely based on the nature of a light source and its underlying spectral characteristics.
To develop a sensor calibration that provides accurate color values across a wide range of ambient lighting scenarios can involve collecting and processing many measurements obtained by exposing an ambient color sensor to many different ambient lighting scenarios. This can make robust and accurate sensor calibration a time-consuming process that is not ideal for implementing a per-sensor factory calibration for ambient color sensors and the electronic devices which incorporate them. Yet per-sensor calibration is very useful towards achieving accurate brightness estimates despite manufacturing variations in spectral response. There is a need for a per-sensor calibration process that is robust and accurate across a wide range of ambient lighting scenarios, while reducing the time required to characterize individual sensors to achieve a factory calibration process that is both accurate and efficient.